Among political professionals and media, it is a settled fact that, in televised debates, appearance matters more than substance. Think of the legend of polished John F. Kennedy defeating sweaty-but-experienced Richard Nixon, or Al Gore annoying America with his incessantly nerdish assaults on good ol’ George Dubya Bush. It was a version of this belief that led conventional wisdom to the immediate conclusion that Mike Pence won his debate against Tim Kaine. Certainly, by theater standards, Pence outperformed his adversary. A polished talk-show host by training, Pence spoke in calm, measured tones and swatted away Kaine’s rapid-fire attacks on his running mate with genial head-shaking or confident-sounding denials.

“Mike Pence’s cool-headed performance on Tuesday night’s debate stage has Republicans wistful that the Indiana governor is not their nominee and hopeful that Pence’s prowess will rub off on Donald Trump before Sunday’s crucial rematch with Hillary Clinton,” reported Politico’s Ben Schreckinger. “More disciplined than Trump, and with a baritone voice that evoked a sense of seriousness, Pence battled back,” observed the Washington Post’s Dan Balz.

One might complain with the voters for prioritizing surface appearance over substance. One might also complain with the news media for internalizing voters’ superficiality and feeding it back to them as theater criticism rather than sorting out the underlying claims. But the fact remains that the rules are the rules, and as they exist, there is usually little penalty for lying incessantly as long as you do it with proper body language and a reassuringly manly baritone.

There is, however, an exception to that rule: You should not lie about things that can be easily disproven with short video clips. So, if Pence had simply insisted that Donald Trump’s tax plan would balance the budget and mostly help the middle class, and that he would allow coal plants to spring up everywhere without impacting the climate, and that his plan would crack down on Wall Street, he’d have walked away the undisputed winner. Instead, Pence claimed over and over again that his running mate had never said the things that Tim Kaine was quoting verbatim. It was all too easy for the Hillary Clinton campaign to respond with this devastating video:

The way debates work is that they play out over time, with an initial impression usually overwhelmed by subsequent messages rippling through the media. In this case, whatever small gains Pence made are likely to be canceled out by days of him looking ridiculous. Lying: It usually works! But not always.